Liquid crystal display

ABSTRACT

A liquid crystal display includes a first substrate, a pixel array, a first pad, a dielectric layer, a filling pattern, a first conductor, a second substrate and a liquid crystal layer. The first substrate has a display area and a pad area located outside the display area. The pixel array is disposed on the display area. The first pad is disposed on the pad area. The dielectric layer has a first opening overlapped with the first pad. The filling pattern is disposed within the first opening of the dielectric layer. The filling pattern has through holes, and the through holes of the filling pattern are overlapped with the first pads. The first conductor is disposed in the first opening of the dielectric layer, and is electrically connected to the first pad via the through holes of the filling pattern.

TECHNICAL FIELD

The invention relates to a display, and more particularly, to a liquidcrystal display.

BACKGROUND

A liquid crystal on silicon (LCOS) display is a liquid crystal displaythat uses a semiconductor process to fabricate a pixel array, a driverintegrated circuit, and other electronic components on a silicon chip.In addition to technical advantages of small pixel size and highresolution, the LCOS display also has the advantages of simple process,low cost and small volume. Therefore, the LCOS display has been widelyused in various electronic products, such as portable cameras,projectors and the like.

In a manufacturing process of the LCOS display, an alignment film needsto be formed on the silicon chip. However, a surface of the silicon chipis mostly uneven. When the alignment film is formed on the unevensurface, a striation defect is likely to occur.

SUMMARY

The invention provides a liquid crystal display with excellentperformance.

A liquid crystal display of the invention includes a first substrate, apixel array, a first pad, a dielectric layer, a filling pattern, a firstconductor, a second substrate and a liquid crystal layer. The firstsubstrate has a display area and a pad area located outside the displayarea. The pixel array is disposed on the display area of the firstsubstrate. The first pad is disposed on the pad area of the firstsubstrate. The dielectric layer is disposed on the pad area of the firstsubstrate, and has a first opening. The first opening of the dielectriclayer is overlapped with the first pad. The filling pattern is disposedwithin the first opening of the dielectric layer. The filling patternhas through holes, and the through holes of the filling pattern areoverlapped with the first pads. The first conductor is disposed in thefirst opening of the dielectric layer, and is electrically connected tothe first pad via the through holes of the filling pattern. The secondsubstrate is disposed opposite to the first substrate. The liquidcrystal layer is disposed between the pixel array and the secondsubstrate.

In an embodiment of the invention, a material of the filling patternincludes a photoresist.

In an embodiment of the invention, the liquid crystal display furtherincludes an alignment film, which is located between the first conductorand the filling pattern.

In an embodiment of the invention, the first pad is electricallyconnected to the second substrate via the first conductor.

In an embodiment of the invention, the liquid crystal display furtherincludes a solder wire and a circuit board. The solder wire is disposedon the first conductor and electrically connected to the firstconductor. The circuit board is electrically connected to the first padvia the solder wire and the first conductor.

In an embodiment of the invention, one of the through holes of thefilling pattern has an aperture D, and 0.3 μm≤D≤10 μm.

In an embodiment of the invention, the first substrate is a siliconsubstrate.

In an embodiment of the invention, a material of the first conductorincludes Ni.

In an embodiment of the invention, the dielectric layer has a secondopening spaced apart from the first opening. The liquid crystal displayfurther includes a second pad and a second conductor. The second pad isdisposed on the pad area of the first substrate, and spaced apart fromthe first pad. The second opening of the dielectric layer is overlappedwith the second pad. The second conductor is disposed in the secondopening of the dielectric layer. The second pad has a surface overlappedwith the second opening of the dielectric layer, and the secondconductor directly contacts and completely covers the surface of thesecond pad.

In an embodiment of the invention, an area of the second pad is smallerthan an area of the first pad.

To make the aforementioned more comprehensible, several embodimentsaccompanied with drawings are described in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a liquid crystal display 10 in anembodiment of the invention.

FIG. 2 is a top view of a pixel array substrate 100 of FIG. 1.

FIG. 3A to FIG. 3E are cross-sectional views showing a manufacturingprocess of the liquid crystal display device 10 according to anembodiment of the invention.

FIG. 4 is a cross-sectional view of a liquid crystal display 10A inanother embodiment of the invention.

FIG. 5 is a top view of a pixel array substrate 100A of FIG. 4.

FIG. 6 is a cross-sectional view of the liquid crystal display 10Acorresponding to a section line I-I′ and a section line II-II′ of FIG.5.

FIG. 7 is a cross-sectional view of a liquid crystal display 10B in yetanother embodiment of the invention.

FIG. 8 is an enlarged schematic diagram of a local portion R of theliquid crystal display 10B of FIG. 7.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of the liquid crystal display 10 in anembodiment of the invention.

FIG. 2 is a top view of the pixel array substrate 100 of FIG. 1.

FIG. 3A to FIG. 3E are cross-sectional views showing a manufacturingprocess of the liquid crystal display device 10 according to anembodiment of the invention. FIG. 3A to FIG. 3E correspond to thesection line I-I′ and the section line II-II′ of FIG. 2.

The manufacturing process of the liquid crystal display device 10 and astructure thereof in an embodiment of the invention will be describedwith reference to FIG. 1, FIG. 2, and FIG. 3A to FIG. 3E.

Referring to FIG. 1, FIG. 2 and FIG. 3A, first of all, the pixel arraysubstrate 100 is provided. The pixel array substrate 100 includes afirst substrate 110, a pixel array 120 and a plurality of pads 131 and132. The first substrate 110 has a display area 110 a and a pad area 110b located outside the display area 110 a. The pixel array 120 isdisposed on the display area 110 a of the first substrate 110. The pads131 and 132 are disposed on the pad area 110 b of the first substrate110. In this embodiment, the pads 131 and 132 may be electricallyconnected to the pixel array 120 located in the display area 110 aand/or other components of the pixel array substrate 100, but theinvention is not limited thereto.

For instance, in this embodiment, the first substrate 110 may be asilicon substrate; the pixel array 120 includes a plurality of pixels;and each of the pixels may include a transistor formed on the siliconsubstrate and a reflective electrode electrically connected to thetransistor. In short, in this embodiment, the pixel array substrate 100may be a silicon chip of a reflective liquid crystal on silicon panel,but the invention is not limited thereto.

The pixel array substrate 100 further includes a dielectric layer 140.The dielectric layer 140 is at least disposed on the pad area 110 b ofthe first substrate 110, and has a plurality of openings 141 and 142.The openings 141 and 142 of the dielectric layer 140 are overlapped withthe pads 131 and 132, respectively.

For instance, in this embodiment, a material of the dielectric layer 140may be an inorganic material (e.g., a silicon oxide, a silicon nitride,a silicon oxynitride, or a stacked layer of at least two of the abovematerials), an organic material or a combination of the above; amaterial of the pads 131 and 132 may be a metal or other conductingmaterial.

Referring to FIG. 1, FIG. 2 and FIG. 3B, next, a plurality of fillingpatterns 151 and 152 are formed on the first substrate 110. The fillingpatterns 151 and 152 are disposed within the openings 141 and 142 of thedielectric layer 140, respectively. In particular, the filling pattern151 has a plurality of through holes 151 a, and the through holes 151 aof the filling pattern 151 are overlapped with the pad 131; the fillingpattern 152 has a plurality of through holes 152 a, and the throughholes 152 a of the filling pattern 152 are overlapped with the pad 132.

For instance, in this embodiment, a full-surface photoresist materiallayer (not shown) may be formed on the dielectric layer 140 and the pads131 and 132; subsequently, a patterning process is performed on thephotoresist material layer to form the filling patterns 151 and 152. Inthis embodiment, a material of the filling patterns 151 and 152 mayinclude a photoresist, but the invention is not limited thereto.

Further, in this embodiment, each of the through holes 151 a and 152 aof the filling patterns 151 and 152 has an aperture D, and 0.3 μm≤D≤10μm. However, the invention is not limited in this regard.

Referring to FIG. 1, FIG. 2 and FIG. 3C, next, an alignment film 160 isformed to cover the pixel array 120, the dielectric layer 140 and thefilling patterns 151 and 152. The alignment film 160 is used to providean anchoring force so that a plurality of liquid crystal molecules in aliquid crystal layer 300 has a specified pre-tile angle when the liquidcrystal display 10 is not enabled.

For instance, in this embodiment, a spin coating method may be used toform the alignment film 160 on the dielectric layer 140 and the fillingpatterns 151 and 152, but the invention is not limited thereto.

It is worth noting that, in this embodiment, the alignment film 160 isformed only after the filling patterns 151 and 152 are filled within theopenings 141 and 142 of the dielectric layer 140; by filling in with thefilling patterns 151 and 152, an upper surface 140 b of the dielectriclayer 140 and top surfaces 151 b and 152 b of the filling patterns 151and 152 can form a relatively even surface so that the striation defectis less likely to occur when the alignment film 160 is formed.

Referring to FIG. 1, FIG. 2 and FIG. 3D, next, a plurality of conductors410 and 420 are formed on the pads 131 and 132. In this embodiment, theconductors 410 and 420 can be initially fixed above the first substrate110 through a colloid 500. For instance, in this embodiment, theconductors 410 and 420 are, for example, Ni balls, and the colloid 500is, for example, a sealant for encapsulating the liquid crystal layer300, but the invention is not limited thereto.

Referring to FIG. 1, FIG. 2 and FIG. 3E, next, the conductors 410 and420 are electrically connected to the pads 131 and 132. For instance, inthis embodiment, while the pixel array substrate 100 and a secondsubstrate 200 are assembled, the second substrate 200 can press down theconductors 410 and 420 so that the conductors 410 and 420 are disposedin the openings 141 and 142 of the dielectric layer 140 and electricallyconnected to the pads 131 and 132 via the through holes 151 a and 152 aof the filling patterns 151 and 152.

It is worth noting that, because the filling patterns 151 and 152 havethe through holes 151 a and 152 a, the conductors 410 and 420 can easilybe electrically connected to the pads 131 and 132 via the fillingpatterns 151 and 152. In other words, while the filling pattern 151 and152 are disposed within the openings 141 and 142 to prevent thestriation defect from occurring, because the filling patterns 151 and152 have the through holes 151 a and 152 a, the disposed fillingpatterns 151 and 152 cannot easily affect the electrical connection ofthe conductors 410 and 420 and the pads 131 and 132.

Further, in this embodiment, the conductors 410 and 420 are electricallyconnected to the pads 131 and 132 via the through holes 151 a and 152 aof the filling patterns 151 and 152 only after the alignment film 160 isformed. Therefore, a portion of the alignment film 160 may remainbetween the conductors 410 and 420 and the filling patterns 151 and 152,but the invention is not limited thereto.

The second substrate 200 is disposed opposite to the first substrate110. For instance, in this embodiment, the second substrate 200 mayinclude a glass substrate and a transparent conductive layer disposed onthe glass substrate. A potential difference between the transparentconductive layer and the reflective electrode of the pixel array 120 maybe used to drive the liquid crystal molecules in the liquid crystallayer 300 so the liquid crystal display 10 can display images. However,the invention is not limited in this regard. According to otherembodiments, the second substrate 200 may also be other structures.

In this embodiment, the conductors 410 and 420 can be used toelectrically connect the second substrate 200 with the pads 131 and 132.That is to say, in this embodiment, the pads 131 and 132 disposed on thefirst substrate 110 can be electrically connected to the secondsubstrate 200 via the conductors 410 and 420, but the invention is notlimited thereto.

Referring to FIG. 1, FIG. 2 and FIG. 3E, next, in this embodiment, avacuum Impregnation may be optionally used to fill the liquid crystallayer 300 in a space surrounded by the pixel array substrate 100, thesecond substrate 200 and the colloid 500. Then, a liquid crystalinjection port (not shown) of the colloid 500 is sealed. At this point,the liquid crystal display 10 of the present embodiment is completed.

Because the filling patterns 151 and 152 are disposed within theopenings 141 and 142 of the dielectric layer 140 of the pixel arraysubstrate 100, the liquid crystal display 10 is less likely to have thestriation defect. More importantly, because the filling patterns 151 and152 have the through holes 151 a and 152 b, the conductors 410 and 420can be electrically connected to the pads 131 and 132 well in themanufacturing process of the liquid crystal display 10 so that theliquid crystal display 10 has normal function and excellent reliability.

In this embodiment, the filling patterns 151 and 152 are provided withinthe openings 141 and 142 of the dielectric layer 140, respectively.However, the invention is not limited in this regard. According to otherembodiments, if the opening of a portion of the dielectric layer 140(e.g., the opening 142) is not large and the opening of the portion ofthe dielectric layer 140 is less likely to cause the streaking defect,it is also possible that the filling pattern (e.g., the filling pattern152) is not provided within the opening of the portion of the dielectriclayer 140. Details regarding the above will be described below withreference to FIG. 4, FIG. 5 and FIG. 6.

It should be noted that the reference numerals and a part of thecontents in the previous embodiment are used in the followingembodiments, in which identical reference numerals indicate identical orsimilar components, and repeated description of the same technicalcontents is omitted. The omitted part of the description can refer tothe foregoing embodiment, which is not repeated in the followingembodiments.

FIG. 4 is a cross-sectional view of the liquid crystal display 10A inanother embodiment of the invention.

FIG. 5 is a top view of the pixel array substrate 100A of FIG. 4.

FIG. 6 is a cross-sectional view of the liquid crystal display 10Acorresponding to a section line I-I′ and a section line II-II′ of FIG.5.

Referring to FIG. 4, FIG. 5 and FIG. 6, the liquid crystal display 10Aof the present embodiment is similar to the liquid crystal display 10described above, and the difference between the two is that, in thisembodiment, the filling pattern 151 is disposed within the opening(e.g., the opening 141) of a portion of the dielectric layer 140, and itis possible that the filling pattern is not disposed within the opening(e.g., the opening 142) of another portion of the dielectric layer 140.

Specifically, in this embodiment, the pads 131 and 132 of the pixelarray substrate 100A include the pad 131 having a larger area and thepad 132 having a smaller area. The opening 141 of the dielectric layer140 overlapped with the pad 131 having the larger area is larger, andthe opening 142 of the dielectric layer 140 overlapped with the pad 132having the smaller area is smaller. It is possible that the fillingpattern is not disposed within the smaller opening 142. That is to say,in this embodiment, the pad 132 has a surface 132 a overlapped with theopening 142, and the conductor 420 can directly contact and completelycover the surface 132 a of the pad 132.

FIG. 7 is a cross-sectional view of the liquid crystal display 10B inyet another embodiment of the invention. FIG. 8 is an enlarged schematicdiagram of the local portion R of the liquid crystal display 10B of FIG.7.

Referring to FIG. 7 and FIG. 8, the liquid crystal display 10B of thepresent embodiment is similar to the liquid crystal display 10 describedabove, and the difference between the two is described as follows.

In this embodiment, a pixel array substrate 100B further includes a pad133 for use in a wire bonding. The dielectric layer 140 further includesan opening 143 overlapped with the pad 133. The liquid crystal display10B further includes a filling pattern 153 disposed within the opening143 of the dielectric layer 140. The filling pattern 153 has a pluralityof through holes 153 a, and the through holes 153 a of the fillingpattern 153 are overlapped with the pad 133. The liquid crystal display10B further includes a conductor 700, which is disposed in the opening143 of the dielectric layer 140 and electrically connected to the pad133 via the through holes 153 a of the filling pattern 153. The liquidcrystal display 10B further includes a solder wire 710, which isdisposed on the conductor 700 and electrically connected to theconductor 700. The liquid crystal display 10B further includes a circuitboard 800. A circuit contact 810 of the circuit boards 800 can beelectrically connected to the pad 133 via the solder wire 710 and theconductor 700. For instance, in this embodiment, the circuit board 800may be a flexible printed circuit (FPC), but the invention is notlimited thereto.

In this embodiment, during the wire bonding, a conductive ball (i.e.,the conductor 700) can be electrically connected to the pad 133 well viathe through holes 153 a of the filling pattern 153 so that the liquidcrystal display 10B has normal function and excellent reliability.

Although the present disclosure has been described with reference to theabove embodiments, it will be apparent to one of ordinary skill in theart that modifications to the described embodiments may be made withoutdeparting from the spirit of the disclosure. Accordingly, the scope ofthe disclosure will be defined by the attached claims and not by theabove detailed descriptions.

1. A liquid crystal display, comprising: a first substrate, having adisplay area and a pad area located outside the display area; a pixelarray, disposed on the display area of the first substrate; a first pad,disposed on the pad area of the first substrate; a dielectric layer,disposed on the pad area of the first substrate, and having a firstopening, wherein the first opening of the dielectric layer is overlappedwith the first pad; a filling pattern, disposed within the first openingof the dielectric layer, wherein the filling pattern has a plurality ofthrough holes, and the through holes of the filling pattern areoverlapped with the first pads; a first conductor, disposed in the firstopening of the dielectric layer, and electrically connected to the firstpad via the through holes of the filling pattern; a second substrate,disposed opposite to the first substrate; and a liquid crystal layer,disposed between the pixel array and the second substrate.
 2. The liquidcrystal display according to claim 1, wherein a material of the fillingpattern comprises a photoresist.
 3. The liquid crystal display accordingto claim 1, further comprising: an alignment film, located between thefirst conductor and the filling pattern.
 4. The liquid crystal displayaccording to claim 1, wherein the first pad is electrically connected tothe second substrate via the first conductor.
 5. The liquid crystaldisplay according to claim 1, further comprising: a solder wire,disposed on the first conductor and electrically connected to the firstconductor; and a circuit board, electrically connected to the first padvia the solder wire and the first conductor.
 6. The liquid crystaldisplay according to claim 1, wherein one of the through holes of thefilling pattern has an aperture D, and 0.3 μm≤D≤10 μm.
 7. The liquidcrystal display according to claim 1, wherein the first substrate is asilicon substrate.
 8. The liquid crystal display according to claim 1,wherein a material of the first conductor comprises Ni.
 9. The liquidcrystal display according to claim 1, wherein the dielectric layerfurther comprises a second opening spaced apart from the first opening,and the liquid crystal display further comprises: a second pad, disposedon the pad area of the first substrate, and spaced apart from the firstpad, wherein the second opening of the dielectric layer is overlappedwith the second pad; and a second conductor, disposed in the secondopening of the dielectric layer, wherein the second pad has a surfaceoverlapped with the second opening of the dielectric layer, and thesecond conductor directly contacts and completely covers the surface ofthe second pad.
 10. The liquid crystal display according to claim 9,wherein an area of the second pad is smaller than an area of the firstpad.